24 



MAINE AGRICULTURAL EXPERIMENT STATION. 



TABLE lo. 



Lactation Record of Dorothy of Orono. 



Lactation Periods. 



Days 

 in milk. 



Pounds 

 of milk. 



Pounds 

 of fat. 



Remarks. 



Sept. 21, 1909— Aug. 4, 1910 

 Sept. 11, 1910— Nov.25,1911 



Feb. 26, 1912— Mar. 24,1913 



316 



440 



391 



7,840.6 

 12,426.4 



7,016.8 



293.62 

 450.75 



253.92 



Lactation in which Ad- 

 vanced Registry record 

 was made. 



Cow was sick for some time 

 during this period. 



After March 24, 1913, the cow never gave any milk. The 

 udder rapidly shrunk to a very small size and the animal began 

 to show the external characteristics of a bull. This change 

 was very slight at first but soon became much more marked. 

 After a lapse of 8 months tJie general external appearance 

 and the behavior of the coiv zvere like those of a bull to a 

 remarkable degree. The neck had become thickened in its 

 posterior parts, and had developed a well marked crest, as is 

 characteristic of a bull. If the cow had been so .'screened that 

 only her forequarters and neck were visiWe any observer would 

 have unquestionably pronounced her a male. The assumption 

 of male characters in these regions was complete and perfect. 

 In the hind-quarters the change from characteristic female 

 conformation in the male direction, while less striking than in 

 the anterior parts, was still clearly evident. The udder shrunk 

 away to a very small size. The hips and rump took on the 

 smooth rounded, filled-out appearance which is characteristic 

 of the bull but not of the cow. 



The cow was slaughtered on February 18, 1914. Autopsy 

 showed as the only gross abnormality a simple cystic condi- 

 tion of the ovaries. Under the microscope these cystic ovaries 

 differed from the normal cow's ovary in but one essential 

 re.=pect, namely that they had no corpora lutea. 



A corpus luteum, or yellow body, is a peculiar cellular struc- 

 ture which forms in the ovaries of animals which give milk, 

 where an ovum has been discharged. This yellow body pours 

 into the blood a chemical substance, which is known to have 

 the function (i) of preventing the ovary from discharging 

 any more ova, and (2) of preventing the animal coming in 

 heat during the course of pregnancy. 



